Clamping or braking devices are known in a wide variety of embodiments for a wide variety of applications. Thus, in EP-A-0 936 366, a braking device for a linear guide is known, which has a carrier body, which can move along a guide rail. The carrier body has brake shoes, which act on the two longitudinal sides. The carrier body has an H shape and a thin, flexible connecting piece and two lower limbs, with which it grips around the guide rail. A brake shoe is arranged between each lower limb and the guide rail. The carrier body is provided with two upper limbs, which, together with the connecting piece, form a receptacle space, in which a force-generating means acting on the upper limbs is provided. Here, the force-generating means can be a toggle lever mechanism that can be activated hydraulically or pneumatically or a piezo-actuator. In addition, a tapered slide valve used as a force transducer can be provided, can be activated hydraulically or pneumatically, and is guided in a space becoming narrower in the longitudinal direction of the braking device between the upper limbs of the carrier body. In all cases, the elastic connecting piece bends due to the application of force on the two upper limbs, so that the two lower limbs with the brake shoes are moved inwards or a greater force is applied to the guide rail.
A disadvantage in this known braking device in connection with the use of an electromechanical transducer, for example, a piezoelement, is particularly its sensitivity to vibrations or other mechanical loads.
The use of a toggle lever mechanism or a tapered slide valve, as well as an electromechanical transducer, means high assembly or manufacturing expense.
In addition, particularly for clamping devices, there is the requirement for sufficiently high clamping forces, which can be realized in known devices only with a relatively high structural and thus financial expense.
From U.S. Pat. No. 5,855,446, a hydraulic clamping sleeve is known, which is aligned on a shaft and can be connected to it, e.g., locked in rotation. The sleeve has an essentially stable sleeve body, which is arranged around a drive shaft at a distance. A pressurized chamber abuts this sleeve body and faces the shaft. A side wall of this chamber, which extends essentially parallel to the shaft, is used here simultaneously as a braking element, which is pressed against the shaft by the expansion of the chamber when the chamber is pressurized, in order to establish a frictionally engaged connection. A Σ-shaped formation of the laterally adjacent walls of the chamber is intended to prevent the sleeve from becoming misaligned relative to the shaft when the chamber is pressurized. In the pressurized state, the Σ-shaped side walls enable expansion of these side walls in the radial direction towards the shaft, even before the increasing chamber pressure also presses the chamber wall running parallel to the shaft against the shaft. Thus, the sleeve can be aligned perpendicular to the shaft axis before the rotationally fixed connection is generated.
This clamping device does not exhibit satisfactory force transfer for generating high contact forces. Furthermore, the chamber is limited in its shape and especially in its possible placement relative to the sleeve body. Braking action can be achieved here only by pressurizing with positive pressure, and the actual brake element, which must possibly transfer high driving forces, is not connected rigidly to the sleeve body, but instead only via the forced relatively unstable pressure chamber.
From WO 01/34990 A1 by the applicant, a clamping and/or braking device is known, in which a base is provided with a chamber, which can be pressurized and which is limited at least in one part of at least one wall section that is flexible but resistant to tensile force and pressure. The limit of the chamber opposite the wall section can also be formed like the first wall section. However, it can also be a rigid part of a body. Preferably, the wall sections lie at a relatively small distance from each other. The forces resulting from the deformation of the chamber are guided at least partially in the direction towards or along the wall section and introduced into a base in the region of the connection of the wall section to this base. If the application point of such points on the base is selected appropriately, and if this base is at least partially elastically deformable, then the forces can be transferred via this base to other points of the base, e.g., in clamping or braking regions. A corresponding braking or clamping means in these regions can then be moved by means of forces into a pressurized position or from this position in order to brake or release a guide element or an element to be clamped or braked. In this way, the application of both positive pressure and also negative pressure in the chamber can be used in order to introduce both tensile and also compressive forces into the base. Obviously, the clamping and/or braking regions can still be engaged with the guide element or the element to be clamped or braked before and after the force introduction, wherein, however, this generates changes in the pressurizing forces between the clamping and/or braking regions and the corresponding other element.
This known clamping and/or braking device starts from the knowledge that when a suitable chamber is pressurized with negative pressure or positive pressure, it tends to deform. If this chamber is formed to a large part from at least one approximately flat wall section, then positive pressure or negative pressure in the chamber first causes deformation in a first direction, which runs essentially perpendicular to this wall section. In order to yield to the deformation (expansion or contraction) in this first direction, this deformation generates contraction or expansion of the chamber accordingly and respectively in a second direction generally perpendicular to the first direction (thus essentially parallel to the wall section). In this way, the fact is used that small forces or deformations in the first direction generate large forces in the second direction, which can be used for braking or clamping or for loosening biased clamping or braking devices.
Finally, from DE 28 48 651 A1, a contracting cell is known, which enables the generation of a linear movement path with a corresponding tensile force in a wide variety of embodiments. The contracting cell can also comprise two spring plates, for example, steel plates, in one embodiment, with a compression chamber, which can be sealed, for example, by means of a bellows, being defined between the plates. By pressurizing the bellows with compressed air, the spring steel plates are bent, so that the lower ends of the two steel plates move in the direction towards the corresponding upper ends. However, at no point does this publication describe the generation of braking and/or clamping forces by means of such a contracting cell.
Starting from the state of the art named above, the invention is based on the problem of designing a clamping and/or braking device, which can be produced with low construction expense and with which sufficiently high braking or clamping forces can be generated in a simple way.